The invention relates to a shackle lock, especially with a long shackle, comprising a lock body and a locking shackle, the end portions of the shackle arms being adapted to fit into respective shackle arm housings until a locked position is reached, and being completely separable from the lock body by withdrawal of the arm end portions from the housings, at least one lock bolt being furthermore guided for movement in the lock body and being pretensioned by biassing means in the direction of an engaged position, so that after the arm end portions have been pushed into their locked position inside the arm housings, they move into the engaged position, engaging thereby into a bolt engagement surface of at least one arm end portion, so preventing withdrawal of this arm end portion from the associated arm housing, there being furthermore provided inside the lock body a key-operated bolt withdrawal mechanism which is connected by a gearing to the lock bolt and which can by means of the key be moved against the action of the biassing means from a basic state corresponding to the engaged portion of the lock bolt and in which the key can be inserted and withdrawn, into a lock-opening state which necessarily produces a disengaged position of the lock bolt.